Chlamydia pneumoniae Serology Is Associated With Thrombosis-Related but Not With Plaque-Related Microembolization During Carotid Endarterectomy

Abstract

Background and Purpose-Chlamydia pneumoniae has repeatedly been associated with atherosclerotic disease. Our study was designed to clarify whether this association is based on C pneumoniae-induced transformation of a stable into an unstable atherosclerotic plaque or on stimulation of hypercoagulability leading to increased thrombotic arterial occlusions by C pneumoniae infection. Transcranial Doppler ultrasonographic monitoring of the middle cerebral artery during carotid endarterectomy offers the opportunity to study, before removal of the plaque, atherothrombotic emboli dislodging from an unstable carotid plaque (plaque-related emboli) and emboli related to (excessive) thrombus formation at the endarterectomy site after removal of the plaque and restoration of flow (thrombosis-related emboli). Methods-C pneumoniae IgA (Ն1/16) and IgG (Ն1/64) seropositivity was assessed in 53 patients with symptomatic carotid artery disease undergoing carotid endarterectomy. The removed carotid plaques were studied histologically to assess plaque instability. Results-Plaque-and thrombosis-related emboli were registered in 43 patients with an adequate transtemporal window.IgA seropositivity (58%) was associated significantly with thrombosis-related embolization (Pϭ0.030) but not with plaque-related embolization or with histological plaque instability. Conclusions-C pneumoniae serology is associated with microembolization after endarterectomy and restoration of flow.Since these microemboli represent platelet aggregations and are related to cerebrovascular complications, our data suggest that C pneumoniae infection contributes to cerebrovascular events in patients with carotid artery disease through stimulation of thrombosis.

Chlamydia pneumoniae and stroke: is there a direct relationship?

“…Such authors remember that the single positivity for pneumoniae is not enough to explain the event of the cerebrovascular process, and conclude that the bacteria has an insignificant role in converting a atherosclerotic plaque into the symptomatic state 21 . In an analysis performed with the serum level of IgA and IgG in the carotid plaque withdrawn by endarterectomy, Vainas et al 22 conclude, in a similar way to our casuistic, that pneumoniae is not related to plaque destabilization. Such authors 22 state that this infectious agent would be related to atherosclerotic phenomena, probably in the first stages of its development, but would not have any role in plaque destabilization.…”

“…In an analysis performed with the serum level of IgA and IgG in the carotid plaque withdrawn by endarterectomy, Vainas et al 22 conclude, in a similar way to our casuistic, that pneumoniae is not related to plaque destabilization. Such authors 22 state that this infectious agent would be related to atherosclerotic phenomena, probably in the first stages of its development, but would not have any role in plaque destabilization. In a recent study, by means of the analysis of carotid plaques obtained through endarterectomy in patients with atherothrombotic stroke, no relation to pneumoniae was detected 12 .…”

Inflammation and Infections as Risk Factors for Ischemic Stroke

“…80 Chlamydial heat shock protein-60 induced the production of TNF-␣ and matrix-degrading metalloproteinases by plaque macrophages, mechanisms that may contribute to plaque rupture and thrombosis. 64 Clinical data support that the presence of C pneumoniae in carotid stenoses increases local thrombogenicity and the risk of infarction, 62,81 but not all results favor this hypothesis. 65 Some [82][83][84][85] but not all 86,87 seroepidemiological studies reported an association between past C pneumoniae infection and asymptomatic carotid atherosclerosis or increased intimamedia thickness.…”

<![CDATA[<B>Vulnerability of atherosclerotic carotid disease</B>: <B>from laboratory to operating room - part 2</B>]]>

“…However, Ieven et al [74] did not observe any differences in the IgG antibodies against chlamydia assessed by immunofluorescence in 106 patients with coronary artery disease and 112 healthy controls, probably due to cross-reactions with other bacteria. On the other hand, Vainas et al [75] described an association between IgA seropositivity and intraoperative thromboembolism in plaques considered histologically stable suggesting that infection by chlamydia can also have a thrombogenic effect in atherosclerosis.…”

“…On the other hand, there is evidence suggesting that thinning of the fibrous cover, the presence of "soft" content or of ulceration give instability to the plaque [103,104], and that the proximity of necrotic regions, specifically if associated to infiltration of macrophages, predispose the patient to clinical events [105]. Moreover, both in models utilizing surface ultrasonography and in more recent studies with computed reconstruction or intravascular ultrasonography, low echogenicity images have been related to necrotic or hemorrhagic content of the plaque [106][107][108], and the degree of calcification is considered to be inversely proportional to the stability of the lesions [75]. It is well known that, for any hemodynamically significant stenosis, patients with less echogenic plaques present with a higher incidence of cerebral infarction.…”